Edit Mode broken

I updated my Concrete5 site to 8.2.1. Since then I am not able to add pages anymore. The page will be added as draft and can be published, but I cannot edit attributes or add blocks.
The Chrome Console prints out:

Uncaught TypeError: html.addClass is not a function
at ConcretePanel.d (app.js:1)
at ConcretePanel.show (app.js:1)
at ConcretePanel.toggle (app.js:1)
at HTMLAnchorElement.<anonymous>(app.js:5)
at HTMLAnchorElement.dispatch (jquery.js:4)
at HTMLAnchorElement.r.handle (jquery.js:4)
at Object.trigger (jquery.js:4)
at HTMLAnchorElement.<anonymous>(jquery.js:4)
at Function.each(jquery.js:2)
at m.fn.init.each(jquery.js:2)